This post describes the first step of comparing Census population data over time: studying documentation to determine the feasibility of variable comparison over time. See Comparing Census Population Data, Part One to get introduced to this project.

As described in the previous post, not all of the population tabulations that are available in the 2000 Decennial Census are available in the 2010 Decennial Census and American Community Survey. Additionally, questions can be asked in different ways, which can make them incomparable.

In addition to determining data comparability, documentation must also be studied to determine variables names, table names and segment identifiers. In order to accomplish this task, I created a table with the following fields:​

The next step was identifying each variable and writing down the information in the template. The table number, table contents, data dictionary reference name, segment, max size, and smallest summary file level is available in the technical documentation as described below:

- Decennial Census 2000 Summary File 1: Starts on page 227 (click here to access the document)- Decennial Census 2000 Summary File 3: Starts on page 422 (click here to access the document)- Decennial Census 2010 Summary File 1: Starts on page 183 (click here to access the document)- American Community Survey 2008-2012 Summary File: Starts on page 46 (click here to access the document)After checking the data documentation/code books to find the variable/table/segment details, I looked up the variables using the following three different Census tools and used the information to fill out the comparability notes in the table:

​After looking all the information up, in the comparability notes of the table, I highlighted the variables that have no comparability concerns as green, I highlighted the variables that have some comparability concerns as orange, and I highlighted the variables that are not comparable as red. Click here to access the completed table.

In order to make information about what variables can be used and at what level, I made a simplified table with our variables of interest, if it can be broken down by race, if the variable can be measured using full population count data or sample data, if it is comparable, the smallest level of geography available, and associated notes. You can find this by clicking here.

This completed my first step of checking the documentation to determine feasibility of comparing variables over time.